In the event of renal failure, it becomes difficult to excrete the final nitrogen metabolites and the like from the human body and they accumulate within the body to cause dysfunction to various organs. For this reason, a medical treatment by artificial dialysis is conducted in order to excrete the accumulated metabolites outside the body. Artificial dialysis is roughly classified into haemodialysis and peritoneal dialysis.
The aim of haemodialysis is to excrete excess water, unwanted solutes, small molecular weight substances like urea and creatinine and other uremic substances in order to correct their levels. Therefore, the usual procedure is that blood is withdrawn from a patient and is passed through a dialyser outside the body using a dialysis fluid. Recently a dialysis fluid mainly containing sodium bicarbonate which is an alkaline agent is used. This haemodialysis treatment is capable of being combined with blood absorption or plasma separation procedures, which is frequently adopted. This treatment has an advantage that it can be applied to patients for a long term period, whereas it has such defects that use of the dialysis apparatus requires a great deal of cost, that patients must have a surgical procedure to provide blood access for blood extracorporeal circulation, that its application is limited to patients who have cardiopulmonary functions strong enough to endure extracorporeal circulation, and so on.
On the other hand, peritoneal dialysis is a method for exchanging solutes and water in capillary vessels of a patient's peritoneal with hypertonic solution which is injected within the peritoneal cavity. The principle of this method is diffusion of solutes which are transferred according to the concentration gradient and water migration due to the osmotic differences. Azotemia, and imbalance of water and electrolytes are corrected by this principle. This method has many advantages such that no special apparatus is commonly required and it gives less influence on the hemodynamics because extracorporeal circulation of the patient's blood is not necessary, and further the peritoneal dialysis is similar to the physiological function of the kidney.
Peritoneal dialyses are usually classified as Continuous Ambulatory Peritoneal Dialysis(CAPD), Intermittent Peritoneal Dialysis (IPD) or Continuous Cyclic Peritoneal Dialysis(CCPD).
The dialysis fluid used for peritoneal dialysis is an aqueous solution which comprises an osmotic agent such as glucose and the like, electrolytes such as sodium, potassium, calcium, magnesium, and organic acid salts such as sodium lactate. These peritoneal dialysis fluids are determined according to the components so as to control the levels of electrolytes or acid-base equilibrium, remove the waste materials and efficiently carry out ultrafiltration.
However, peritoneal dialysis fluids have heretofore been maintained at acidic pH, 4.5 to 5.5, for their compositional stability and their osmotic pressure has been rendered hypertonic for dialyzing effects, that is the osmotic pressure ratio to physiological saline is about 1.1 to 1.6. Clinically, dialysis fluids which are unsuitable for the human body are intraperitoneally injected in large amounts, for instance about 10 L/human/day and pooled in the peritoneal cavity for several hours, for instance 2 to 24 hours. Accordingly, there is a defect that patients who are subjected to dialysis tend to suffer peritonitis, etc., accompanied by clinical symptoms such as stomach ache, and finally peritoneal sclerosis, etc. (Wakabayashi, Y. and Kawaguchi, Y.; "Peritoneal Dialysis and Sclerosing Encapsulating Peritonitis", Igaku No Ayumi (Progress in Medical Science), 183, 363-367, 1997). Occurrence of peritoneal sclerosis decreases the degree of effectiveness of dialysis, which makes it difficult for patients suffering kidney diseases to use peritoneal dialysis for a long term period. Further there are defects that plasma proteins are lost and the period of dialysis is very long and so on.
Under these circumstances, the present invention has been made and, therefore, an object of the present invention is to provide a peritoneal dialysis fluid that can suppress the occurrence of peritonitis.